The hemodynamic response to pulmonary embolism in patients without prior cardiopulmonary disease

Abstract

The hemodynamic status of 20 patients free of prior cardiopulmonary disease was related to the degree of pulmonary embolic obstruction estimated by selective pulmonary angiography. Angiographic estimation of obstruction ranged from 13 to 68 percent. Systemic arterial hypoxemia occurred in virtually all patients (95 percent) including those with only 13 percent obstruction, thus suggesting that angiographically detectable emboli virtually do not occur without producing systemic hypoxemia. Mean pulmonary arterial pressure was increased in 14 patients (70 percent) and was consistently increased when obstruction exceeded 30 percent. Elevation of the level of mean right atrial pressure was found in 10 patients (50 percent) and was usually associated with obstruction in excess of 35 percent and mean pulmonary arterial pressure in excess of 30 mm Hg. Good correlation was observed between mean pulmonary arterial pressure and angiographic estimation of obstruction (P < 0.01), mean right atrial pressure and obstruction (P < 0.01), mean pulmonary and right atrial pressures (P < 0.01), and pO 2 and obstruction (P < 0.05). Cardiac index was characteristically normal or mildly increased, being below the lower limit of normal in only 4 patients (20 percent). In patients who had not experienced cardiac failure, the cardiac index appeared to increase as systemic arterial pO 2 decreased (P < 0.01) once hypoxemia was well established. Mean pulmonary arterial pressure never exceeded 40 mm Hg, despite massive obstruction in some patients, thereby suggesting that this level approximates the maximal pressure response of the previously normal right ventricle.